This analysis tests for seven genetic variations in the CYP2C9 and VKORC1 genes.

Reasons for Referral:
1. Patients starting initial treatment with Warfarin.
2. Patients already treated with Warfarin who are experiencing difficulty in achieving therapeutic INR
3. The results of this test can be used in available algorithms to determine appropriate Warfarin dosing (example www. Warfarindosing.org)

Limitations:
1. Not all variants with known impact on enzyme expression and activity are tested in this assay.
2. Non-genetic factors, variations in the other genes involving the drug metabolism or drug interactions are not measured by this assay.
3. Rare genetic alterations at primer binding sites may result in diagnostic errors.